The general field of this invention relates to skin barriers for ostomy, wound drainage, incontinence, and similar uses. For such applications, the barriers are used in the form of molded rings, sheets, or strips, which are applied to protect the skin from the bodily fluid being discharged and to provide a liquid seal. The desirable physical properties of such barrier compositions are diverse, and it has been difficult to achieve all of the desirable properties in combination.
The skin barrier should be soft and flexible, while at the same time providing a degree of elasticity and having the ability to maintain its shape. For initial application, the barrier should have "dry tack", so that the barrier will provide an initial adhesive adherence to the skin. The adhesiveness should also be maintained while the barrier is in contact with an aqueous fluid, such as urine, intestinal or fecal fluids. This is usually referred to as "wet tack".
Skin barriers should also provide mechanical endurance when subjected to bodily fluids. Absorption of the fluid is desirable, but the amount of absorption should be controlled so that undue swelling of the composition does not occur. Excessive swelling can distort the form of the barrier causing it to separate from the skin and break the moisture seal so that the barrier can no longer effectively perform its sealing function. However, if no swelling occurs fluid accumulates between the barrier and the skin and again a separation of the barrier from the skin may occur. Further, penetration of fluid between the barrier and the skin can increase the amount of skin irritation.
Another important consideration is that the barrier should have as long a useful life as possible. This permits the user to leave the barrier in place for a number of days, or in some cases for a week or longer. Moreover, frequent replacement of the barrier increases the cost and inconvenience to the user, and can contribute to irritation of the skin in the area to which the barrier is applied.
For many years there has been a continuing search for improved barrier compositions. One of the early successful compositions was composed of a gelled mixture of karaya gum and glycerin. This composition is still in commercial use, especially in intestinal ostomy applications (viz. ileostomies and colostomies). Such compositions are also used in the form of wound barrier blankets for wound drainage applications, and have been marketed in irradiation-sterilized form for this purpose. However, when karaya is subjected to gamma irradiation, such as for the purpose of sterilization, the irradiation degrades the karaya, decreasing its mechanical strength. To compensate for this effect, in applications where sterilization is important, it has been proposed to incorporate a polyacrylamide resin in the karaya-glycerin formula. See U.S. Pat. Nos. 4,306,551 and 4,307,717. Polyacrylamide resin has also been formulated with glycerin or other polyol, and cross-linked by irradiation, as disclosed in U.S. Pat. No. 4,258,715.
Skin barrier compositions composed of mixtures of elastomers and hydrocolloids are also known, and have been used commercially. See, for example, U.S. Pat. Nos. 3,339,546 and 4,253,460. With this type of barrier composition, the elastomer, which may be a natural or synthetic rubber, or mixtures of such rubbers, comprises the continuous phase, and the hydrocolloid is dispersed therein in particulate form. Both natural hydrocolloid gums such as karaya, pectin, and gelatin, and synthetic hydrocolloids such as carboxymethyl cellulose have been used in varius admixtures. The elastomer such as polyisobutylene provides the compositions with an adhesive dry tack characteristic. The dispersed particles of hydrocolloid absorb water, and also when wet acquire a wet tack adhesive characteristic. Such formulations have been sterilized by gamma irradiation, but such sterilization degrades the polyisobutylene which does not cross-link. Sterilization is thus accomplished at the expense of downgrading desirable physical properties. Such downgrading due to loss of strength by irradiation has tended to limit the marketing of barriers in sterile forms.